Derivatized reduced malto-oligosaccharides

ABSTRACT

Disclosed are derivatized malto-oligosaccharides and methods for the preparation thereof. In accordance with the disclosed invention, a malto-oligosaccharide is hydrogenated to thereby obtain a hydrogenated malto-oligosaccharide, and the resulting hydrogenated malto-oligosaccharide is derivatized, such as via oxidation, esterification, etherification, or enzymatic modification. The derivatization of such hydrogenated malto-oligosaccharides results in a surprisingly low level of a formation of by-products and products of degradation. In a particularly preferred embodiment of the invention, a mixture of malto-oligosaccharides is catalytically hydrogenated under reaction conditions suitable to substantially preserve the degree of polymerization (DP) profile of the mixture. The resulting malto-oligosaccharide mixture then is derivatized to form a derivatized malto-oligosaccharide mixture.

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention is directed towards malto-oligosaccharidederivatives, and towards methods for the preparation thereof. Morespecifically, the invention is directed in its preferred embodimentstowards malto-oligosaccharides that have been derivatized by oxidation,etherification, esterification, or enzymatic modification.

BACKGROUND OF THE INVENTION

[0002] Oligosaccharides are commonly prepared by the controlledhydrolytic cleavage of starches. In the production of sucholigosaccharides, the glycosidic linkages of the starch molecules arepartially hydrolyzed to yield at least one oligosaccharide species, andmore typically, a mixture of oligosaccharides species. Oligosaccharidemixtures so prepared typically include at least onemalto-oligosaccharide species. Malto-oligosaccharides are characterizedas having a saccharide backbone that comprises predominantly 1-4glycoside linkages.

[0003] Malto-oligosaccharides comprise a commercially important class ofcarbohydrates that fall within the general class of reducingcarbohydrates, which are carbohydrates that include an acetal group thatis in equilibrium with its respective aldehyde or ketone. Suchmalto-oligosaccharides find numerous commercial applications.Derivatized malto-oligosaccharides also are known in the art. Suchderivatized malto-oligosaccharides also have many commercial uses,including, for example, encapsulants, acidulants, flocculants,adhesives, antiredeposition agents, detergent builders, and so forth.

[0004] The prior art has provided numerous processes for thederivatization of malto-oligosaccharides. Known processes areconventional and typically comprise derivatizing themalto-oligosaccharide via a conventional derivatizing process to form aderivatized product. Such prior art processes suffer from a number ofdrawbacks, however. For example, when subjected to certain reactionconditions, such as alkaline conditions, malto-oligosaccharides candegrade and/or undergo numerous side reactions to form respectivelyundesired products of degradation or reaction by-products. Suchby-products and products of degradation lead to poor reaction yields,undesired color formation, and difficulties in purifying the desiredderivatized malto-oligosaccharides.

[0005] It is believed that the so-called “alkaline peeling reaction,” inwhich the reducing end sugar of a malto-oligosaccharide degrades intosmaller molecules, contributes substantially to degradation andby-product formation in the derivatization of malto-oligosaccharides. Inrecognition of this alkaline peeling reaction, the prior art has taughtin other contexts to convert a base saccharide to a glycoside, tothereby incorporate a protecting group. For example, it is known toincorporate a methyl protecting group at the reducing end of glucose tothereby form the alkaline-stable methyl glycoside. Another approach usedin the prior art is the use of non-reducing sugars such as sucrose andtrehalose as protecting groups. For example, U.S. Pat. No. 5,780,620(Mandai et al.) purports to disclose non-reducing oligosaccharideswherein one or several glucosyl groups are bound to both glucosyl groupsin trehalose. While the use of protecting groups such as sucrose ortrehalose in connection with the preparation of a glycoside may affordan alkaline-stable product, the process of preparing such stabilizedmalto-oligosaccharides can be laborious and not economically attractive.

[0006] It is a general object of the present invention to provide amethod for derivatizing a malto-oligosaccharide. In accordance withpreferred embodiments of the invention, by-product formation andformation of products of degradation are mitigated as compared withproducts formed by known malto-oligosaccharide derivatization reactions.It is also a general object of the invention to provide a derivatizedmalto-oligosaccharide product.

THE INVENTION

[0007] The invention is premised upon the surprising discovery thatreduced malto-oligosaccharides not only are alkaline-stable with respectto unmodified malto-oligosaccharides, but also may be derivatized toform derivatized malto-oligosaccharides with a surprising decrease inby-products and products of degradation, and further providing otherunexpected benefits, including improved yields and improved ease ofpurification. Further surprising in conjunction with the derivatizationof a mixture of malto-oligosaccharides is the discovery that the changein DP profile of the mixture upon oxidation, and, it is believed, otherderivatization, is smaller in conjunction with reducedmalto-oligosaccharides as compared with unmodifiedmalto-oligosaccharides. Thus, not only does the derivatization ofreduced malto-oligosaccharides generally result in relatively lessformation of by-products and products of degradation, relativelyincreased yield, and ease of purification with regards to unmodifiedmalto-oligosaccharides, the DP profile of the derivatizedmalto-oligosaccharide mixture generally will be relatively closer tothat of the starting mixture.

[0008] In accordance with the invention, a method for preparing aderivatized malto-oligosaccharide is provided. Generally, the methodcomprises the steps of providing a hydrogenated malto-oligosaccharide,and derivatizing the hydrogenated malto-oligosaccharide to thereby forma derivatized malto-oligosaccharide. The malto-oligosaccharide may beobtained via the steps of providing the malto-oligosaccharide andhydrogenating the malto-oligosaccharide to thereby obtain a hydrogenatedmalto-oligosaccharide. Derivatized malto-oligosaccharides prepared inaccordance with the method of the invention also fall within the scopeof the invention. The scope of derivatization encompassed by theinvention is not contemplated to be limited, and thus, for example, thehydrogenated malto-oligosaccharides may be derivatized via oxidation,esterification, etherification, or other suitable derivatizationreaction. The hydrogenated malto-oligosaccharide also may be modifiedenzymatically to yield enzymatically modified malto-oligosaccharides.

[0009] In a particularly preferred embodiment of the invention, amixture of hydrogenated malto-oligosaccharide is derivatized. Mostpreferably, the mixture is obtained via the hydrogenation of a mixtureof malto-oligosaccharides under reaction conditions suitable tosubstantially preserve the DP profile of the reaction mixture, as taughtin co-pending application Ser. No. PCT/US99/01098.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0010] The method of the invention is generally contemplated to beapplicable to any malto-oligosaccharides species or mixture of aplurality of malto-oligosaccharides species. By “malto-oligosaccharide”is contemplated any species comprised of plural saccharide units linkedpredominately via 1-4 linkages, thus including, for example,maltodextrins and syrup solids. In preferred embodiments of theinvention, at least 50% of the saccharide units in themalto-oligosaccharide are linked via 1-4 linkages. More preferably, atleast about 60% saccharide units are linked via 1-4 linkages; even morepreferably, at least about 80% of the saccharide units are so linked.Malto-oligosaccharides are contemplated to include saccharides specieshaving an odd DP value, such as maltotriose.

[0011] Malto-oligosaccharides may be characterized by their degree ofpolymerization (DP), which refers to the number of saccharide monomerunits in each molecule. Each malto-oligosaccharide saccharide speciesalso may be characterized by its dextrose equivalent value (DE), whichgenerally indicates the proportion of aldehyde, hemiacetal, or ketonegroups in the molecule. Malto-oligosaccharides having a DE less than 20prior to hydrogenation are known as maltodextrins, whereasmalto-oligosaccharides having a DE of 20 or greater are known as syrupsolids. The invention is contemplated to find particular applicabilityin connection with the derivatization of mixtures of a plurality ofmalto-oligosaccharides species. The malto-oligosaccharides species inthe mixture may be different at least in DP value, thus defining a DPprofile for the mixtures. The DP profile may be partially defined by asaccharides species having a DP value of 1, for example, dextrose orsorbitol. The mixture further may include other saccharides species orother components.

[0012] Preferably, in conjunction with the derivatization of a mixtureof malto-oligosaccharides, at least a portion of themalto-oligosaccharides species in the mixture has a DP value greaterthan 5, and more preferably, at least one of the malto-oligosaccharidesspecies in the mixture has a DP value of 8 or more. More preferably, atleast one species has a DP value of at least 10. For example, inpreferred embodiments of the invention, at least 80% of themalto-oligosaccharides species in the mixture have a DP greater than 5,and at least 60% may have a DP greater than 8. In another embodiment, atleast 80% of the malto-oligosaccharides species have a DP greater than10. In some embodiments of the invention, the DP profile of themalto-oligosaccharides mixture is such that at least 75% of themalto-oligosaccharides species in the mixture have a DP greater than 5and at least 40% species in the mixture have a DP greater than 10. Suchstarting materials may be obtained conventionally, for example, by thepartial hydrolysis of starch.

[0013] Suitable malto-oligosaccharides are sold as malto-dextrins underthe trademark MALTRIN® by Grain Processing Corporation of Muscatine,Iowa. The MALTRIN® malto-dextrins are malto-oligosaccharide products,each product having a known typical DP profile. Suitable MALTRIN®malto-dextrins that may be derivatized in accordance with the presentinvention include, for example, MALTRIN® M040, MALTRIN® M050, MALTRIN®M100, MALTRIN® M150, and MALTRIN® M180. Typical approximate DP profilesfor the subject MALTRIN maltodextrins are set forth in the followingtable (the DP profiles being approximate as indicated in the table):Typical DP profile (% dry solids basis) DP profile M180 M150 M100 M050M040 DP>8 46.6 ±4% 54.7 ±4% 67.8 ±4% 90.6 ±4% 88.5 ±4% DP 8 3.9 ±2% 4.8±1.5% 4.5 ±1.5% 1.5 ±1% 2.0 ±1% DP 7 9.5 ±2% 9.1 ±1.5% 7.0 ±1.5% 1.5 ±1%2.4 ±1% DP 6 11.4 ±2% 8.4 ±1.5% 6.1 ±1.5% 1.4 ±1% 1.8 ±1% DP 5 5.9 ±2%4.7 ±1.5% 3.3 ±1.5% 1.3 ±1% 1.3 ±1% DP 4 6.4 ±2% 5.5 ±1.5% 3.7 ±1.5% 1.1±1% 1.4 ±1% DP 3 8.3 ±2% 6.7 ±1.5% 4.2 ±1.5% 1.0 ±1% 1.4 ±1% DP 2 6.2±2% 4.8 ±1% 2.5 ±1% 0.8* ±1% 0.9* ±1% DP 1 1.8 ±1.5% 1.3 ±1% 0.7* ±1%0.8* ±1% 0.3* ±1%

[0014] The invention encompasses the derivatization of maltodextrinstarting materials that have substantially the foregoing approximate DPprofiles, however made. Other malto-oligosaccharides suitable for use inconjunction with the invention include other malto-dextrins, such asMALTRIN® M440, MALTRIN® M510, MALTRIN® M550, MALTRIN® M580, MALTRIN®M700, as well as corn syrup solids such as MALTRIN® M200 and MALTRIN®M250 (these having a DE>25 prior to hydrogenation). The invention is notlimited to derivatization of the foregoing malto-oligosaccharidesspecies or mixtures, and indeed, any suitable malto-oligosaccharide maybe derivatized in conjunction with the invention.

[0015] Most preferably, the mixture of malto-oligosaccharides iscatalytically hydrogenated to thereby substantially reduce themalto-oligosaccharides in the mixture, in some cases to a DE ofessentially zero, as set forth in more detail in co-pending applicationSer. No. PCT/US98/01098 (published as WO 99/36442). By “substantiallyreduced” is meant that the DE of the malto-oligosaccharide is reduced byat least about 85%, and preferably at least about 90%, relative to theinitial DE thereof. The term “essentially zero” as used herein withrespect to DE value refers to hydrogenated product having a DE of lessthan about 1. Further details concerning catalytic hydrogenation ofmalto-oligosaccharide mixtures are set forth in the aforementionedco-pending application Ser. No. PCT/US98/01098.

[0016] While is not intended to limit the invention to a particulartheory of operation, it is believed that the reducing end group at theleading C-1 position of the malto-oligosaccharide aldose is generallythe most reactive group on the molecule. When an unmodifiedmalto-oligosaccharide is derivatized, for example, by oxidation, it isbelieved that oxidation will occur first at this position, followed byoxidation at the primary alcohol (C-6) positions on the molecule.Because the rate of the reaction is higher at the C-1 reducing endgroup, alternative degradation mechanisms may occur by the time the C-6alcohols are oxidized. When the reducing end group is hydrogenated toform the corresponding alditol, however, this phenomenon is mitigatedagainst. All of the primary alcohol groups on the malto-oligosaccharidesmolecule will oxidize at similar rates, thus limiting the amount ofby-product formation. As the degree of polymerization of themalto-oligosaccharides increases, the number of C-6 groups increasesrelative to the single leading C-1 group on the malto-oligosaccharidemolecule, thus leading to proportionally greater benefits.

[0017] In accordance with the invention, the malto-oligosaccharide isderivatized, by which generally is contemplated incorporating one ormore substituents or chemical modifications in one or more positions onone or more saccharide units in the malto-oligosaccharide molecule. Theextent of the derivatization can be expressed via the degree ofsubstitution (DS) of the malto-oligosaccharide. In conjunction with theinvention, it is possible to derivatize the malto-oligosaccharide to aDS of greater than or equal to 0.25, even more preferably, a DS of about0.5 and even more preferably, a DS greater than about 0.8. Whereapplicable, the extent of derivatization may be expressed in terms ofmolar substitution (“MS”), for example, in the case ofhydroxyalkylation. The extent of derivatization may be adjusted to thedegree desired for a given application. Surprisingly, it has been foundthat the use of hydrogenated malto-oligosaccharides often affords aproduct that has a higher DS than that which would be obtained viaderivatization of an unmodified malto-oligosaccharide under similarreaction conditions. The invention is applicable to the derivatizationof mixtures of malto-oligosaccharides, wherein at least a portion of themalto-oligosaccharides in the mixture are derivatized. By “at least aportion” is contemplated any portion of the malto-oligosaccharides,including without limitation the derivatization of some or allmalto-oligosaccharides of a given DP value.

[0018] While the invention is applicable to any derivatization via anysubstituent, the invention finds particular applicability to thosederivatization chemistries that employ alkaline conditions. Particularlysuitable derivatizations include oxidations, etherifications, andesterifications. The invention is also applicable to enzymaticmodifications of the malto-oligosaccharide, which enzymaticmodifications may result in an oxidized, etherified, esterified orotherwise derivatized or modified malto-oligosaccharide. Generally, anyreaction conditions that will result in a derivatizedmalto-oligosaccharide, except possibly highly acidic conditions thatmight allow for hydrolysis of glycosidic linkages, may be employed. Themalto-oligosaccharide preferably is derivatized in aqueous solution at apH greater than about 6.0, and more preferably under alkaline conditions(i.e., a pH grater than 7.0).

[0019] For example, with respect to derivatization the oxidation of themalto-oligosaccharide in one or more primary alcohol positions to formcarboxylic acids, a variety of oxidation reactions are known in the artand are applicable for use in conjunction with the invention. Suitableoxidizing reactants include nitroxyl radicals, nitrogen dioxide andtetroxide, and hydrogen peroxide. Alternatively, the oxidation may alsobe effectuated enzymatically or via electrolytic methods. Suitable suchreactions are disclosed in Arts et al., Synthesis 1997 (6): 597-613;Roper, in Carbohydrates As Organic Raw Materials, Ch. 13: 267-288(1991); and in published International Application No. WO 95/07303.

[0020] In accordance with a preferred embodiment of the invention, themalto-oligosaccharide is oxidized in the presence of a metal catalyst,such as platinum or palladium. The oxidation of glucose using palladiumon carbon doped with bismuth has been described in EP 142,725 and inU.S. Pat. No. 4,845,208, and the oxidation of starch hydrolysates hasbeen disclosed in U.S. Pat. No. 4,985,553 and in published InternationalApplication No. WO 97/34861. Platinum is preferred over palladium foroxidizing alcohol groups, inasmuch as platinum is less prone todeactivation by oxygen. However, platinum-catalyzed oxidation ofdextrose to yield glucaric acid traditionally has been plagued with highlevels of by-product formation, In EP 775,709, a method of combiningnoble metal catalysis with an electrodialysis separation is disclosed.Other oxidations known in the art include those disclosed in Glattfeldand Gershon, J. Am. Chem. Soc. 60:2013 (1938); Heynes and Paulsen, Ang.Chem. 69:600 (1957); Heynes and Beck, Chem. Ber. 91:1720 (1958); U.S.Pat. No. 5,109,128; EP 548,339. WO 95/07303 (use of2,2,6,6,-tetramethylpiperdine 1-oxyl in conjunction with an oxidantsystem that includes sodium bromide and sodium hypochlorite to oxidizecarbohydrates selectively at the C-6 position at pH's ranging from 9.8to 11.5), and WO 92/18542 (alkaline oxidation in the present of metalions in molecular oxygen, and a polydentate and amine ligand).

[0021] The invention also is contemplated to be applicable toetherification of malto-oligosaccharides. Preferred etherificationreactions include ethoxylations, propoxylations, and similaralkoxylations, as well as reactions to introduce a cationic charge byusing reagents such as 3-chloro-2-hydroxypropyl-trimethyl ammoniumchloride or like reagents. Any suitable reagents in reaction conditionsas are known or as may be found to be suitable may be used inconjunction with the invention. For example, reagents such as octylbromide, allyl bromide, propylene oxide, ethylene oxide, and likechemicals conventionally used in connection with ether formation may beemployed, as well as higher molecular weight polymers conventionallyused in epoxide ring opening or nucleophilic displacement reactions,such as glycidyl ethers, and so forth. The etherification reaction maycomprise combining the malto-oligosaccharide and alkylene oxide in anyamount effective to achieve derivatization. In one embodiment, thealkylene oxide is present in an amount greater than 40% by weight of themalto-oligosaccharides starting material, such as an amount greater than45% by weight of the malto-oligosaccharide starting material. Thereaction conditions may be any conditions suitable to form amalto-oligosaccharide-alkyl ether.

[0022] Another example of the derivatization of a malto-oligosaccharideis via esterification. The esterification reaction preferablyincorporates any acyl group having from 2 to 20 carbon atoms. The acylgroup may be added via conventional means, such as using an acidchloride or acid anhydryde, or by such other means as may be found to besuitable. The malto-oligosaccharide may be esterified to form anacetate, benzoate, octenylsuccinate, or other suitable ester. A commonesterification reaction in which a hydrogenated malto-oligosaccharidewould be advantageous is an octenyl-succinylation reaction, such as thatdisclosed in U.S. Pat. No. 5,720,978.

[0023] The malto-oligosaccharide also may be derivatized via enzymaticmodification. Any suitable enzyme as may be known or may be found to besuitable may be used in conjunction with the invention to modify themalto-oligosaccharide. It is contemplated that the enzymaticmodification may result in a malto-oligosaccharide that is oxidized,esterified, or otherwise derivatized or modified. The term “derivatized”in conjunction with an enzymatically modified malto-oligosaccharide isintended to encompass such modifications as may be effected by theenzymatic modification.

[0024] The following non-limiting Examples are provided to illustratepreferred embodiments of the present invention.

EXAMPLES Example 1 Oxidation of Malto-Oligosaccharide

[0025] In 651 ml of deionized water was slurried 1.79 grams 10% platinumon graphite (Johnson Matthey type B101026-10). The slurry was heated to60° C. while purging with nitrogen (1.5 L/min). Once the slurry reachedtemperature, 14.7 grams hydrogenated MALTRIN® M180 was added. Thenitrogen flow was replaced with 0.2 L/min oxygen. The reaction pH wascontrolled at pH 9.0 with 0.5M NaOH. Once 0.25 equivalents of NaOH wasconsumed (5 hours), the oxygen flow was terminated and the sample wasdiluted to 2 liters, then vacuum filtered through #3 Whatman filterpaper, frozen, and freeze dried. The samples were analyzed for ash andfor carboxyl degree of substitution via a conventional titrametricprocess. MALDI (matrix-assisted laser desorption ionization) massspectra was obtained.

[0026] As a control, 14.8 grams unmodified MALTRIN® M180 was oxidizedunder similar reaction conditions. After 5 hours and 49 minutes, 0.127equivalents of NaOH was found to have been consumed. The followingresults were obtained: Analysis Example 1 Control Ash 2.18 6.83 DS 0.2060.322 Degree of Polymerization (DP) Sample Molecular Weight Example 1Control (Derivatized (Derivatized MALTRIN ® Hydrogenated MALTRIN ® UnitsM180 MALTRIN ® M180) M180) Major Peak Minor Peak Major Peak Minor Peak 3 530  565  545  527  549 4  690  727  692  689  728 5  851  890  853 851  891 6 1013 1052 1014 1013 1052 7 1175 1214 1176 1175 1214 8 13371376 1337 1339 — 9 1498 1499 1538 1501 — 10 1660 1660 1700 1662 — 121985 1984 2021 1988 — 14 2308 2308 2346 2310 — 16 2632 2630 2669 2632 —18 2955 2954 2992 2954 — 20 3281 3277 — 3276 — 26 4244 4241 — — — 416678 — — — —

[0027] The degree of substitution was higher for the control because theuncontrolled oxidation reaction created more carboxyl groups asdegradation products.

[0028] The color of the product of Example 1 was significantly less thanthat of the control. The mass spectra indicated a significant drop inthe overall molecular weight and DP profile of both of the oxidizedsamples, but a significantly greater preservation of molecular weightwith the product of Example 1, with the maximum observed peak given as4241 daltons for example 1, and 3276 daltons for the control.

Example 2 Propoxylation of Malto-Oligosaccharide

[0029] In a 500 ml reaction flask, which was equipped with a magneticstirrer, a temperature control, and a condenser, 200 grams hydrogenatedmaltodextrin (MALTRIN® M180) was dissolved in 60 grams deionized water.To this solution was added 5.6 grams potassium hydroxide and 62.8 gramspropylene oxide. The reaction mixture was refluxed for 16 hours, andallowed to heat to 65° C. Once the reaction reached temperature, it wasterminated with the addition of 7 grams sodium bisulfite. The finalreaction mixture had an orange color. The reaction mixture wasion-exchanged on a dual column system of 150 ml DOWEX® MONOSPHERE 66(hydroxide form) and 150 ml DOWEX® MONOSPHERE 88 (hydrogen form), andthen freeze dried to give a white product.

[0030] As a control, 140 grams MALTRIN® M180 was similarly propoxylated.The reaction mixture was a dark orange to brown color after terminationwith sodium bisulfite. After ion exchanging and freeze drying, the givenproduct had a yellow color.

[0031] Each product was evaluated for hydroxypropyl degree ofsubstitution via a conventional technique. The following results wereobtained: Analysis Example 2 Control 2 DS 0.93 .46

[0032] The color of the control was significantly greater than theproduct of Example 2. No significant difference in maximum molecularweight was observed. The propoxylation reaction of the present inventionthus yielded a product having significantly less color and higher DS ascompared with the control.

Example 3 Carboxymethylation of Malto-Oligosaccharide

[0033] Fifty grams of hydrogenated MALTRIN® M100 was dissolved in 100 mlwater. Monochloroacetic acid (0.5 equivalents) was added, followed by24.2 grams of 50% NaOH (1.0 equivalent) The mixture was heated to 70° C.and held at this temperature for 2 hours. After 2 hours, the pH wasmeasured and found to be 11.2, after which the pH was adjusted to afinal pH of 8.0 with the addition of 6N HCl. The reaction contents werecooled and then slowly poured into 2000 liters methanol to precipitate abeige-colored solid. The solid was washed with a second 200 ml aliquotof methanol and dried under vacuum for 2 days to yield 58.1 grams of aproduct which contained 13.4% moisture and 5.75 ash. Theash-moisture-corrected theoretical yield of the product was 85%. The DSwas determined via a conventional titrametric process and was found tobe 0.30. MALDI molecular weight analysis demonstrated a maximummolecular weight of 2241 daltons and strong evidence of mono-, di- andtri-substituted carboxymethylation of the malto-oligosaccharidemolecules.

[0034] As a control, 50 grams of MALTRIN® M100 was carboxymethylated ina similar reaction. After the initial reaction mixture had been held for2 hours, the reaction pH was found to be 8.0. The precipitated solid wasdark yellow, and the dry solid yield was 35.3 grams product whichcontained 11.2 percent moisture and 4% ash. The ash-andmoisture-corrected theoretical yield was 54%, and the DS was found to be0.22. The maximum molecular weight was found to be 1236 daltons, and themass spectra analysis gave some evidence only for mono-substitution. Thecontrol had significantly more color than the product of Example 3. ThisExample illustrates that a higher DS, better recovery, betterpreservation of molecular weight, and better color were obtained withhydrogenated malto-oligosaccharides in accordance with the inventionthan the control.

Example 4 Hydroxypropyl Trimethylammonium Chloride Derivatization ofMalto-Oligosaccharide

[0035] Two hundred grams (dry solid basis) of hydrogenated MALTRIN® M100was dissolved in 280 ml water. To this solution was added 24.0 grams ofa 50% solution (0.24 equivalents) sodium hydroxide over a period of 10minutes. QUAB 151 (2,3 epoxypropyl-n,n,-trimethylammonium chloride,DeGussa Corp.) 214.0 grams of a 70% solution (0.8 equivalents) was addedto the reaction and the temperature was maintained at 60° C. for threehours. After three hours the reaction mixture was a rusty brown color.The solution was pH-adjusted to 6.0 with HCl and freeze dried to yield340 grams of a light brown solid. The unpurified, recovered yield aftermoisture and ash correction was 88%. MALDI molecular weight analysisindicated a maximum molecular weight about 1603 daltons.

[0036] As a control, 200 grams unmodified MALTRIN® M100 was similarlyderivatized. After three hours, the reaction mixture was found to beblack and viscous. The purified, recovered yield was 92%, but MALDImolecular weight analysis indicated a maximum molecular weight of about1330 daltons. The control had significantly more color than the Example.Both the products of Example 1 and of the control were substituted toabout the same extent, as evidenced by nitrogen combustion analysis.Thus, the Example provided a product with less color, and betterpreservation of molecular weight than the control.

[0037] All of the foregoing examples illustrate that an improvedproduct, with improved ease of purification (as evidenced by the lowercolor levels), may be obtained using hydrogenatedmalto-oligosaccharides.

Example 5 Enzymatic Modification of Malto-Oligosaccharide

[0038] Hydrogenated MALTRIN® M180, 50 g, is dissolved in 25 g of waterand pH controlled at 7.0. Vinyl acetate, 5 g, is poured into thereaction mixture and the system stirred vigorously. Porcine pancreaticlipase, 5 g, is added and the reaction is stirred for 24 hours atambient temperature. The resulting maltodextrin is isolated byprecipitation by ethanol, and dried to yield a partially acetylatedproduct.

[0039] While particular embodiments of the invention have been shown, itshould be understood that the invention is not limited thereto sincemodifications may be made by those skilled in the art, particularly inlight of the foregoing teachings. It is, therefore, contemplated by theappended claims to cover any such modifications as incorporate thosefeatures which constitute the essential features of these improvementswithin the true spirit and scope of the invention. All references andcited herein are hereby incorporated by reference in their entireties.The disclosure of co-pending application Ser. No. PCT/US98/01098 also ishereby incorporated by reference in its entirety.

What is claimed is:
 1. A mixture of derivatized malto-oligosaccharidespecies prepared by a method comprising the steps of: providing amixture of a plurality of malto-oligosaccharide species; catalyticallyhydrogenating said mixture under hydrogenation conditions suitable tosubstantially preserve the DP profile of said mixture to thereby obtaina hydrogenated malto-oligosaccharide mixture, wherein said mixture ishydrogenated to DE of essentially zero; and derivatizing saidhydrogenated malto-oligosaccharide mixture to thereby form saidderivatized malto-oligosaccharide mixture.
 2. The mixture of claim 1,said derivatizing comprising oxidizing said mixture.
 3. The mixture ofclaim 1, said derivatizing comprising estherifying said mixture.
 4. Themixture of claim 1, said derivatizing comprising etherifying saidmixture.
 5. The mixture of claim 1, said derivatizing comprisingenzymatically modifying said mixture.
 6. A mixture of derivatizedmalto-oligosaccharide prepared by a method comprising the steps of:providing a hydrogenated malto-oligosaccharide mixture, said mixturehaving been prepared by catalytically hydrogenatizing a mixture ofmalto-oligosaccharide species to a DE of essentially zero underhydrogenation conditions suitable to substantially preserve the DPprofile of said mixture; and derivatizing said hydrogenatedmalto-oligosaccharide mixture to thereby form said derivatizedmalto-oligosaccharide mixture.
 7. The mixture of claim 6, saidderivatizing comprising oxidizing said mixture.
 8. The mixture of claim6, said derivatizing comprising estherifying said mixture.
 9. Themixture of claim 6, said derivatizing comprising etherifying saidmixture.
 10. The mixture of claim 6, said derivatizing comprisingenzymatically modifying said mixture.
 11. A method for preparing amixture of derivatized malto-oligosaccharides, comprising the steps of:providing a hydrogenated malto-oligosaccharide mixture, said mixturehaving been prepared by catalytically hydrogenatizing a mixture ofmalto-oligosaccharide species to a DE of essentially zero underhydrogenation conditions suitable to substantially preserve the DPprofile of said mixture; and derivatizing said hydrogenatedmalto-oligosaccharide mixture to thereby form said derivatizedmalto-oligosaccharide mixture.
 12. The method of claim 11, saidderivatizing comprising oxidizing said mixture.
 13. The method of claim11, said derivatizing comprising estherifying said mixture.
 14. Themethod of claim 11, said derivatizing comprising etherifying saidmixture.
 15. The method of claim 11, said derivatizing comprisingenzymatically modifying said mixture.